This looks incredible! There are so many things you are doing well, I don’t know where to start. It looks like you have a great understanding of form, shape, and values already. In fact, with this piece, I only have one thing I can find that could be improved! His face is just slightly wider on the right side of the page. An easy way to see if this or something similar has happened in your art is to flip your canvas while drawing digitally! Otherwise, I would take a look at it again in an hour or have someone else take a look to see what is “off” about it. The reason this works is because when we are working on a piece, our brain starts to trick us into thinking that what we are looking at is correct because it has seen it for so long.
Hopefully that helps! Thanks for sharing your art and doing your best to improve!
Hopefully that helps! Thanks for sharing your art and doing your best to improve!